Atoms, isotopes and elements?

Question

I don't understand how scientists knew there were such a thing as atoms and isotopes a hundred years ago. They can't be seen through the most powerful microscope. How can you possibly know that this element has 6 neutrons, that one 12 and they can change when they want. How did they see this?

Answer 1

Actually, a hundred years ago, they didn't know about neutrons. The properties of atoms were worked out from chemistry experiments. This gave the relative masses of the different atoms. Then statistical mechanics allowed the computation of Avagdro's number, which gave the actual masses of the different atoms. Electrons were known from cathode rays and from electricity, but the actual charge of an electron was a rather delicate experiment done by Milikan in 1909 (a bit less than 100 years ago). From studies of cathode rays, the ratio of the mass of an electron and it's charge was known. From the basics of charges, it was then possible to determine the number of electrons in an atom. At first it was suspected that the charge in the nucleus (which was determined from scattering experiments like those of Rutherford) was a combination of protons and electrons. The neutron wasn't discovered until 1932. Most of the stuff that is known about the nucleus was discovered since then.

Answer 2

if you're in school, you'll learn that 2 years from now, by force of course (hey that Rhymezz!). if you're not, then go *%&$ someone! stupid.

scientists a hundred years ago used stuff like alpha and beta beams, blasting them on gold, or using electrostatic theories and experiments, or using magnetic pulses. that way little by little we got what we now call the atomic theory. and by the way, YOU CAN"T SEE AN ATOM THROUGH A MICROSCOPE!!.

peace

Answer 3

well.. um... the atomic theories kinda explained a part of it... these small particles usually explains how things behave...
atoms, isotopes and elements are proven to exist through experiments conducted...
well... chemistry is just like magic... it has secrets yet to be discovered

Answer 4

u know, the theory on atoms pretty much started out as a notion. but in the later years, it was accepted for fact becoz it kinda explained the behavior of elements and stuff.

Answer 5

Table of Elements came from trying to make "GOLD", it was later realized that Gold is NOT an ALLOY (combined metal), but, a pure form, an element cannot be broken down to anything like a simple compound, it is pure.